The LC-75 vaccine strain of the IBD virus was obtained from Pan African Vaccine Quality Control (PANVAC), with a titer of TCID50 × 106. The virus was grown on chicken fibroblasts prepared from 12-day-old embryonated eggs at the National Veterinary Institute (NVI). After the virus was harvested and pooled, the antigen was purified from the cell debris by centrifugation (Beckman Coulter Avanti J-E Centrifuge) at 14000 rpm, and the resulting supernatant was used for coating.
